The methods of treatment by passing current through the skin of the human body are known per se and are outside the scope of the present invention. The currents are passed into the skin between one or a plurality of cutaneous electrodes, generally formed by rigid or elastically deformable conducting plates, connected to a first terminal of a generator provided to produce currents of form and direction defined by the method of treatment, and one or more counter-electrodes connected to a second terminal of the generator. The counter-electrodes may be similar to the cutaneous electrodes, or constituted by supple pads impregnated with a physiologically neutral conducting liquid. The action of the currents penetrating in the skin under the cutaneous electrodes is often reinforced by oiling the skin with pharmacologically active compositions, whilst the counter-electrodes used for the return of the currents towards the generator have an essentially neutral behaviour.
It will be specified that the cutaneous electrodes considered in the present case are fundamentally different from electrodes used as contacts intended for recording electric signals of organic origin, such as cardiogram or encephalogram signals, these contacts being very localized and provided to transmit signals of minimum power, whilst the cutaneous electrodes may cover extensive regions of the body and must transmit appreciable powers to the organism, with superficial power densities which are balanced in all the regions involved. Whilst the contacts must aim essentially at minimising the contact potentials, the cutaneous electrodes must aim at the balanced distribution of the currents in the regions involved, under conditions where the contact potentials have a negligible influence.
The current cutaneous electrodes have the drawback that the plates, even if they are elastic, do not strictly follow all the contours of the skin, especially if the regions in question have prominent projections or recesses, or bony ridges or delicate or sensitive parts, where the application of pressures capable of bringing the skin and the electrode into mutual conformation, is unacceptable. Facial treatments are particularly difficult from this point of view. Now, the treatment of the skin is effective only where it is in contact with the cutaneous electrode, so that, with currently used electrodes, there is a risk of irregularities of treatment showing zones with visible boundaries, possibly aggravated by a danger of local burns in zones where there is an excessive concentration of current. Furthermore, the treatment of broad extents of skin, for example from the waist to the ankles, requires a plurality of electrodes which are difficult to place and fix contiguously, and of which the suitably balanced coupling to the generator requires a bulky network of conductors which is difficult to adjust.
French patent application No. 75 15622 describes compositions of electrodes designed to be applied directly on the skin of patients for the purposes of electrical stimulation to act on pain and motricity, which compositions comprise a resinous binding agent with which is mixed a certain quantity of electrically conducting powder, and similar to conducting paints used for industrial electrical applications. The resinous binding agents are chosen such that, under the conditions of use, particularly in solution, they are neither toxic, nor irritant, nor allergenic and adhere to the skin, in three classes comprising acrylovinyl resins, polyether urethanes and polyvinyl acetates, whilst the conducting powders are grains of silver, gold or platinum, or a graphite powder. The compositions are normally positioned in the form of paints with dermatologically acceptable solvents such as acetone, ethanol, isopropanol and the like. As a variant, the acrylovinyl compositions containing silver powder may make adhesive coatings on sheets of paper or metal.
On combining the scattered teachings of the above-mentioned French patent application, it is understood that the cutaneous electrodes form very supple films, whose thickness ranges between a few micrometers to a few tens of millimeters, which are provided to occupy localized zones of the body, such as joints, and typically the wrist, and remain there for several days (three days at minimum) so as to be able to carry out a series of sessions of treatment. The adhesion of the conducting films is determined by a prior degreasing of the skin. Moreover, the cutaneous electrodes thus produced are provided for relatively localized treatments, this resulting from the fact that the skin must be stretched for the application, which can only be effected in restricted zones. Furthermore, the application of continuous films, even having a certain permeability to water vapour, over extensive regions of the body and for several consecutive days, would be capable of provoking skin lesions.
It is therefore appreciated that the cutaneous electrodes described in the above-mentioned French patent application are generally not suitable for replacing the electrodes constituted by rigid or elastic plates mentioned previously in the description of the state of the art for the application of methods of therapeutic or aesthetic treatments by the passage of currents in the skin to which the present invention refers, and which envisage treatments of the skin or subjacent tissues, over extensive regions of the body, including the face.